222 
8 4 
NEMATOGENE. 
Filaments without a sheath distinct from 
the trichome ‘< a # 
6B Filaments apalatinated 3 in small “dloak. 
ing bundles. 7 . 
Filaments formed of one or sean coloared 
trichomes enclosed in a transparent sheath, 
from which the trichomes emerge to repro- 
duce new filaments . : 
Sheath containing several trichomes, at least 
in the larger filaments é . < 
A. Filaments growing in eoatbausa 
creeping, erect, or floating wick- 
like bundles z is é . 
B. Filaments bundled, erect, growing 
in small rounded tufts, or in felt. 
like tarf of indefinite extent. 
Trichomes very slender . 
Sheath enclosing only a single trichome : 
A. Filaments simple, or only excep- 
tionally exhibiting the beginning 
of ramification where the tri- 
chome issues from the side of 
the sheath . ‘ ¢ 
6 Filaments auelutinatal in 
wick-like bundles . 
B. Filaments branched. Ramifications 
produced by the branching of the 
trichome outside the sheath, very 
irregular, and often geminate, as 
iv Scytonema 3: ‘ 
(Trichomes of which the cells 
only multiply in the direction 
of the length of the filament 
Trichomes of which the cells 
multiply as well in the direc- 
10 ScrtonEMEE tion of the breadth of the 
filament, at least where the 
branches, which are always 
produced by lateral sa ae 
cation, originate . 
L 
A. Cells of the trichome often gemi- 
nate or ternate in consequence 
of their lateral multiplication, or 
even forming transverse several 
celled bands. Sheath large. Cells 
surrounded with a thick mem- 
brane very prominent in the old 
filaments. Hormogones origina- 
ting in lateral branchlets formed 
of a single row of cells . 
8 Filaments of the hormogones 
much slenderer than the 
principal filament, and origi- 
nating in unilateral tufts 
Oscillaria. 
Trichodesmium. 
Microcoleus. 
Inactis. 
: A. B. 
Lnyngbya. 
Symploca, 
Plectonema. 
1l 
Stigonema. 
. Fischera. 
